westad and e



A. G. WESTAD AND E. L. HRGG;

ClRCULATlNG APPARATUS FOR CELLULOSE DIGES TERS.

' APPLICATION FILED MAR. 8.1919.

Patented July 8, 1919.

Muentor-s 42G. WQ Z'a/d EL. #5 95.

Juan/leg enonvomi u" CIMULATIHG -r n eona i digester or to the lye. in the manner hitherto practised, the lye at the bottom of the diester will always be weaker (thinner) than 1n the top of the apparatus, because the lye does not circulate in the proper way. It will stream upward in the central part'of the digester and downward along the sides of the same at a proportional slow rate- The result is; that the preparation of the mass will befaster finished in the upper part of the digester than in the lower, which also involves a prolongated digesting time and a heterogeneous product. When the digest ing is performed indirectly by means of tube coils, etc., inside of the digester, this drawback i-savoided, because the circulation takes place-at a faster rate, as the lye streams upward'along thesides of the dige'ster,- and downward in, the central part. The indirect digesting implies however the employment of steam tube coils inside of the digester, which coils very soon will get a covering, which highly 1 decreases the heat transmission,and therefore must be removed at short intervals of time.

The present invention has for its object a circulating apparatus, at which the advantagesof the indirect digesting are obtained by use of direct steam supply,

The invention is shown in the accompany Ting drawing which shows e length section through a dlgester comprising the new on culating apparatus. I r The lower part of the digester is formed .likc acylinder 1 with bottom lid -2- and with one or more steam inlets 3-'. Into this cylinder-the circulating apparatus is inserted& This is formed as a hollow cylinder 4- of somewhat lesser diameter than the cylinder '-1-, whereby an annular compartment 5-, the steam is let in.

' The inner cylinder 4 has on its outer epeciseeflonoi Letters Patent. Application eice'r fisrtn e, leis. serial in. silence.

is formed into. which won, sentences Lore-serene.

side some ribs '-''i-, which are bent into the Shane of a screw thread and will impart a fast rotating movement to the steam before it enters the lower, openings '7 of e; set (row) pi. tubes -8 which are facing the dlregtion of the rotation and are arrangednii the outside of the upper part of the cyllnder k lead upward into the digester and here are directed aslant outward along the inner conical well of the digester.

The cylinder terminates on its top in a strainer .--9-,

When the steam is let into the digester through the tubes 8-, it has the direction of thc arrows. It ie forced outward toward the outer wall of the digester and upwerd along this wall, whereby the lye is driven into the same direction, thus being forced to stream downward in the central part, through'the strainer into the interior of the cylinder, down to the bottom 2, out through the side openings 10- in the cylinder l, whereupon it again is forced icy the inflowing steers and rotat ing will ascend into the intermediate compertinent In this way a lively and efi'ective circulation of the lye is obtained during the entire time of digesting as also an intimate interconnection hetween the steam and the lye, a homogeneous product and a shorter time of Patented July e, role;

digesting. lit is also possible to work at lower digesting temperature than customary.

Claims;

1. In a circulating apparatus for cellulose digesters, body having-n cylindrical lower portion provided with steam inlets a closure for said. lower portion, a cylinder in the lower portion of the body providing a steam compartment and having openings at its lower end, a strainer at the upper end of the cylinder and means for directing the course of the steam and lye supplied to the body to insure of a continuous circulation or" the lye and steam upwardly along the wells -ofthe body and downwardly through the center thereof and through the cylinder.

2. A device as claimed in claim 1 wherein the means includes tubes arranged between the cylinder anc b lower cylindrical portion of the digester body.

3. A device as claimed in claim 1 where- 1n the means comprisesspiral ribs'on the outer surface of the cylinder and Wllllllgbni steam compartment and angulerly bent tubes between the eylinder and the upper edge. of the cylindrical portion of the body.

4 I nf ppa t s of the character de 5 scribed, e digester body having a cylindrical lower portionprovided with steam inlets, a closure for-said lower portion, a, cylinder etreiner govering the upper end of the cylmier; splrel llbS on the outer surface of the eylinder and in the steam compartment, and

.a plurality of tubes arranged between the cylinder and the lower portion of the body having their lower portions open and feeingthe direction of passages of the'steam in the compartment and having their upper ends bent ang'ularly and projecting into the main portion of the body of the digeeter.

In testimony whereof we affix our signetures in the presence of two witnesses..

Witnesses:

AXEL, LAHN, HANS HALL. I 

